International Rectifier / Infineon IRF MOSFET are available at Mouser Electronics. Mouser offers inventory, pricing, & datasheets for International Rectifier. IRF Transistor Datasheet, IRF Equivalent, PDF Data Sheets. MOSFET. Parameters and Characteristics. Electronic Component Catalog. 25 Aug Е Uses IRF data and test conditions. Source-Drain Ratings and Characteristics. Parameter. Min. Typ. Max. Units. Conditions. V(BR)DSS.
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The goal at the moment is to minimize R5r as much as Q5r will allow; its value was selected to drive about 2A into Q5r ‘s gate when Q5r is to be off, and when we want Q5r on, maximize the efficiency of the path to ground.
I’m still thinking about how to speed up turning Q5r back on. A simple voltage doubler circruit can be built to pump up a small capacitor to about 24V, irff4905 that can be dumped into the P MOSFET with an N-type at the appropriate time. CrossRoads on Jan 30, This has consequences though; when the PMOSFET is on, all current through the resistor is shunted to ground – which produces more current than wanted via that route, so I thought maybe increasing the resistance when the PMOSFET is on, and decreasing it when it’s off would mitigate that.
Some drivers do have an always-on charge-pump though, you’d have to search for irf495 right part.
I’m working on an automotive project which will use an Arduino as a controller. Have you looked at purpose made Automotive High Side Switches? Lots of interesting stuff there.
Most of such devices cannot PWM, they take ‘s of us to switch. I’ve also tentatively added in D5s and R5s.
When the main transistor is off, its gate must be about 12V, so the source of Q5s is about 12V and Vgs now is going to be negative – the transistor is driven on hard. You will have to draw a LOT of current through Q5b before you can get Q5s down to a voltage where you can switch it off.
MarkT on Jan 30, Mark, Tom, thank you both for your comments. One thing I can think that maybe should be included is a way to create a slight delay in Q5b turning off so Q5s can turn off Q5r a little “harder”?
Perhaps a voltage divider which selects resistance to ground – likely through an “inverted” Q5b I’d be happy to hear of other or additional ways to minimize turn-off times while minimizing heat production from any components. MorganS Shannon Member Posts: If limiting the voltage swing to turn it off works, maybe limiting the voltage swing to turn it back on would also work.
We here have the problem that there is only an unclean 12V supply to work with, with spikes and dips, and standard high-side drivers for n-MOSFETs lrf4905 clean stable 12V to work with.
I’ve done some more thinking, and have come up with something else; no idea if it’d work, but what the heck, throw it out there and see what sticks.
Now with Unlimited Eagle board sizes! Irr4905 why most people just use packaged solutions. TomGeorge Design and Repair of industrial control systems. Lots ifr4905 hints, allusions, partial answers, etc. Irf905 on Jan 30, What I know so far: The following shows the conventional way to pull-up a PMOSFET’s gate in “c”and a theoretical way to speed it up and mitigate wasted power in “e”: It is likely neither one will work as-is.
So, I came up with again, “c” is a “common” approach and “e3” is my latest incarnation: Without knowing as much as necessary or learning a ton of the calcs required to make complete sense of everything, I’ve read lots on this here and elsewhere and have not been able to find any complete answers.
Commenting on variation “e” directly above: MarkT Brattain Member Posts: MorganS on Jan 31, Everything runs on smoke, let the smoke urf4905, it stops running It can drive 6,pF in 40ns at 6A.
Gentlemen may prefer Blondes, but Real Men prefer Redheads! However, when it’s on, most current is routed through this resistor, so heat becomes a concern. So, limit the lower voltage to something that will turn it on completely, and minimize the voltage swing necessary to shut it back off – maybe 1.
I don’t understand hardly any of “5”and have only partially figured out the push-pull arrangement in “3”so I’m not sure ief4905 any irf4095 the supporting components in either circuit missing, in excess, mis-valued, etc.
It’s a tad pricey, but if this becomes a 2-chip solution To mitigate this heat production, reductions in switching times are required; here are two discrete-component approaches which I’ve cobbled together from suggestions and circuits I’ve found in various places: However, making them too small incurs inefficiencies – and likely the resistors will produce too much heat themselves.
While I have experienced some glimmerings of understanding, I don’t know how far off I am with either the “5” or “3” circuits. I’ve come up with a couple of other ways to speed up turning off Q5rbut they were tending to get irf4950 complex than I’d like. For igf4905 part, the requirements are: I did a Google search on these forums which produced a lot of topics on this; I’ve read every one of them and even irt4905 my own.
Hi, What is the load? I’m aware that the specified components irf4095 not be optimal and there are likely support components missing, but this is just to see if this could work in theory. Yes you want this, but how do you switch it off?
So, D5s is there to limit voltage at the gate to 10V, and R5s is there to ensure it doesn’t release too much magic smoke the shown value should keep it to around 0.